ABSTRACT
The existence of a potent vasoconstrictor peptide secreted by endothelial cells was initially demonstrated in 1985,1 but it was Yanagisawa et al.2 who isolated and cloned the 21-amino acid peptide endothelin (ET) shortly afterwards. Several ETs have since been discovered, called ET-1, ET-2, and ET-3, as well as bigger 31-amino acid peptides. ET-1 is the most abundant ET produced in blood vessels and the one this chapter is concerned with, whereas ET-3 is mainly a neuropeptide. ET-1 is released normally by endothelial cells toward underlying smooth muscle,3 upon which it exerts its vasoconstrictor effects.
